This paper provides a review of some asymptotic methods for construction of nonlinear normal modes for continuous system (NNMCS). Asymptotic methods of solving problems relating to NNMCS have been developed by many authors. The main features of this paper are that (i) it is devoted to the basic principles of asymptotic approaches for constructing of NNMCS; (ii) it deals with both traditional approaches and, less widely used, new approaches; and (iii) it pays a lot of attention to the analysis of widely used simplified mechanical models for the analysis of NNMCS. The author has paid special attention to examples and discussion of results. Keywords Nonlinear oscillations . Normal mode . Asymptotic approach . Continuous system 1 Definition of nonlinear normal modes for continuous system First definition of nonlinear normal modes for continuous system (NNMCS) is based on exact separation of spatial and time variables [1]. Exact separation of spatial and time variables is possible for some simplified models of continuous systems (Kirchhoff model of nonlinear beam [2], Berger model of nonlinear plate [3,4], Berger-like model of shallow shell [5-7]) for simply supported ends. Naturally, solutions of this type were constructed earlier [2], but Wah was the first who pointed to links between these solutions and those proposed by R.M. Rosenberg for discrete system concepts of NNM [8][9][10]. Naturally, area of applicability of Wah definition is very restricted.Shaw and Pierre proposed the following definition of NNMCS [11]: "If the displacement u 0 (t) = u(s 0 , t) and velocity v 0 (t) = v(s 0 , t) of a single point, s = s 0 , are known, then the entire displacement and velocity field can be determined by the dynamics of that single point u(s, t) = U (u 0 (t), v 0 (t), s, s 0 ), v(s, t) = V (u 0 (t), v 0 (t), s, s 0 )."